Your links can include UTM parameters so that Google Analytics (and other analytics platforms) can better understand where your website traffic is coming from.
When you switch the feature on, by default the parameters will be set to make sure Google Analytics shows all traffic from Linktree to be 'Social' instead of 'Referral'.
This is typically what most users expect traffic from Linktree to display as, given Linktree traffic will primarily be from Instagram. You can also set custom URL parameters if you prefer.
To turn on UTM parameters, navigate to the 'Analytics' section found in the 'Settings' tab in your Admin page and click the toggle on.